diff options
| -rw-r--r-- | clippy_lints/src/large_stack_frames.rs | 106 | ||||
| -rw-r--r-- | tests/ui-toml/large_stack_frames/large_stack_frames.rs | 2 | ||||
| -rw-r--r-- | tests/ui-toml/large_stack_frames/large_stack_frames.stderr | 17 | ||||
| -rw-r--r-- | tests/ui/large_stack_frames.rs | 17 | ||||
| -rw-r--r-- | tests/ui/large_stack_frames.stderr | 64 |
5 files changed, 136 insertions, 70 deletions
diff --git a/clippy_lints/src/large_stack_frames.rs b/clippy_lints/src/large_stack_frames.rs index b397180a69c..059ba981ef3 100644 --- a/clippy_lints/src/large_stack_frames.rs +++ b/clippy_lints/src/large_stack_frames.rs @@ -1,10 +1,12 @@ -use std::ops::AddAssign; +use std::{fmt, ops}; -use clippy_utils::diagnostics::span_lint_and_note; +use clippy_utils::diagnostics::span_lint_and_then; use clippy_utils::fn_has_unsatisfiable_preds; +use clippy_utils::source::snippet_opt; use rustc_hir::def_id::LocalDefId; use rustc_hir::intravisit::FnKind; use rustc_hir::{Body, FnDecl}; +use rustc_lexer::is_ident; use rustc_lint::{LateContext, LateLintPass}; use rustc_session::impl_lint_pass; use rustc_span::Span; @@ -108,13 +110,25 @@ impl Space { } } -impl AddAssign<u64> for Space { - fn add_assign(&mut self, rhs: u64) { - if let Self::Used(lhs) = self { - match lhs.checked_add(rhs) { - Some(sum) => *self = Self::Used(sum), - None => *self = Self::Overflow, - } +impl fmt::Display for Space { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Space::Used(1) => write!(f, "1 byte"), + Space::Used(n) => write!(f, "{n} bytes"), + Space::Overflow => write!(f, "over 2⁶⁴-1 bytes"), + } + } +} + +impl ops::Add<u64> for Space { + type Output = Self; + fn add(self, rhs: u64) -> Self { + match self { + Self::Used(lhs) => match lhs.checked_add(rhs) { + Some(sum) => Self::Used(sum), + None => Self::Overflow, + }, + Self::Overflow => self, } } } @@ -123,10 +137,10 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackFrames { fn check_fn( &mut self, cx: &LateContext<'tcx>, - _: FnKind<'tcx>, + fn_kind: FnKind<'tcx>, _: &'tcx FnDecl<'tcx>, _: &'tcx Body<'tcx>, - span: Span, + entire_fn_span: Span, local_def_id: LocalDefId, ) { let def_id = local_def_id.to_def_id(); @@ -138,22 +152,68 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackFrames { let mir = cx.tcx.optimized_mir(def_id); let param_env = cx.tcx.param_env(def_id); - let mut frame_size = Space::Used(0); + let sizes_of_locals = || { + mir.local_decls.iter().filter_map(|local| { + let layout = cx.tcx.layout_of(param_env.and(local.ty)).ok()?; + Some((local, layout.size.bytes())) + }) + }; - for local in &mir.local_decls { - if let Ok(layout) = cx.tcx.layout_of(param_env.and(local.ty)) { - frame_size += layout.size.bytes(); - } - } + let frame_size = sizes_of_locals().fold(Space::Used(0), |sum, (_, size)| sum + size); + + let limit = self.maximum_allowed_size; + if frame_size.exceeds_limit(limit) { + // Point at just the function name if possible, because lints that span + // the entire body and don't have to are less legible. + let fn_span = match fn_kind { + FnKind::ItemFn(ident, _, _) | FnKind::Method(ident, _) => ident.span, + FnKind::Closure => entire_fn_span, + }; - if frame_size.exceeds_limit(self.maximum_allowed_size) { - span_lint_and_note( + span_lint_and_then( cx, LARGE_STACK_FRAMES, - span, - "this function allocates a large amount of stack space", - None, - "allocating large amounts of stack space can overflow the stack", + fn_span, + &format!("this function may allocate {frame_size} on the stack"), + |diag| { + // Point out the largest individual contribution to this size, because + // it is the most likely to be unintentionally large. + if let Some((local, size)) = sizes_of_locals().max_by_key(|&(_, size)| size) { + let local_span: Span = local.source_info.span; + let size = Space::Used(size); // pluralizes for us + let ty = local.ty; + + // TODO: Is there a cleaner, robust way to ask this question? + // The obvious `LocalDecl::is_user_variable()` panics on "unwrapping cross-crate data", + // and that doesn't get us the true name in scope rather than the span text either. + if let Some(name) = snippet_opt(cx, local_span) + && is_ident(&name) + { + // If the local is an ordinary named variable, + // print its name rather than relying solely on the span. + diag.span_label( + local_span, + format!("`{name}` is the largest part, at {size} for type `{ty}`"), + ); + } else { + diag.span_label( + local_span, + format!("this is the largest part, at {size} for type `{ty}`"), + ); + } + } + + // Explain why we are linting this and not other functions. + diag.note(format!( + "{frame_size} is larger than Clippy's configured `stack-size-threshold` of {limit}" + )); + + // Explain why the user should care, briefly. + diag.note_once( + "allocating large amounts of stack space can overflow the stack \ + and cause the program to abort", + ); + }, ); } } diff --git a/tests/ui-toml/large_stack_frames/large_stack_frames.rs b/tests/ui-toml/large_stack_frames/large_stack_frames.rs index 39798ffea49..a612e56570f 100644 --- a/tests/ui-toml/large_stack_frames/large_stack_frames.rs +++ b/tests/ui-toml/large_stack_frames/large_stack_frames.rs @@ -10,7 +10,7 @@ fn f() { let _x = create_array::<1000>(); } fn f2() { - //~^ ERROR: this function allocates a large amount of stack space + //~^ ERROR: this function may allocate 1001 bytes on the stack let _x = create_array::<1001>(); } diff --git a/tests/ui-toml/large_stack_frames/large_stack_frames.stderr b/tests/ui-toml/large_stack_frames/large_stack_frames.stderr index c23fac14564..19983e2f3e8 100644 --- a/tests/ui-toml/large_stack_frames/large_stack_frames.stderr +++ b/tests/ui-toml/large_stack_frames/large_stack_frames.stderr @@ -1,13 +1,14 @@ -error: this function allocates a large amount of stack space - --> tests/ui-toml/large_stack_frames/large_stack_frames.rs:12:1 +error: this function may allocate 1001 bytes on the stack + --> tests/ui-toml/large_stack_frames/large_stack_frames.rs:12:4 | -LL | / fn f2() { -LL | | -LL | | let _x = create_array::<1001>(); -LL | | } - | |_^ +LL | fn f2() { + | ^^ +LL | +LL | let _x = create_array::<1001>(); + | -- `_x` is the largest part, at 1001 bytes for type `[u8; 1001]` | - = note: allocating large amounts of stack space can overflow the stack + = note: 1001 bytes is larger than Clippy's configured `stack-size-threshold` of 1000 + = note: allocating large amounts of stack space can overflow the stack and cause the program to abort = note: `-D clippy::large-stack-frames` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::large_stack_frames)]` diff --git a/tests/ui/large_stack_frames.rs b/tests/ui/large_stack_frames.rs index f32368f9397..e6c030b8a9e 100644 --- a/tests/ui/large_stack_frames.rs +++ b/tests/ui/large_stack_frames.rs @@ -1,3 +1,5 @@ +//@ normalize-stderr-test: "\b10000(08|16|32)\b" -> "100$$PTR" +//@ normalize-stderr-test: "\b2500(060|120)\b" -> "250$$PTR" #![allow(unused, incomplete_features)] #![warn(clippy::large_stack_frames)] #![feature(unsized_locals)] @@ -23,8 +25,7 @@ impl<const N: usize> Default for ArrayDefault<N> { } fn many_small_arrays() { - //~^ ERROR: this function allocates a large amount of stack space - //~| NOTE: allocating large amounts of stack space can overflow the stack + //~^ ERROR: this function may allocate let x = [0u8; 500_000]; let x2 = [0u8; 500_000]; let x3 = [0u8; 500_000]; @@ -34,17 +35,21 @@ fn many_small_arrays() { } fn large_return_value() -> ArrayDefault<1_000_000> { - //~^ ERROR: this function allocates a large amount of stack space - //~| NOTE: allocating large amounts of stack space can overflow the stack + //~^ ERROR: this function may allocate 1000000 bytes on the stack Default::default() } fn large_fn_arg(x: ArrayDefault<1_000_000>) { - //~^ ERROR: this function allocates a large amount of stack space - //~| NOTE: allocating large amounts of stack space can overflow the stack + //~^ ERROR: this function may allocate black_box(&x); } +fn has_large_closure() { + let f = || black_box(&[0u8; 1_000_000]); + //~^ ERROR: this function may allocate + f(); +} + fn main() { generic::<ArrayDefault<1_000_000>>(); } diff --git a/tests/ui/large_stack_frames.stderr b/tests/ui/large_stack_frames.stderr index b99500fd9c3..f2e0a127f5f 100644 --- a/tests/ui/large_stack_frames.stderr +++ b/tests/ui/large_stack_frames.stderr @@ -1,42 +1,42 @@ -error: this function allocates a large amount of stack space - --> tests/ui/large_stack_frames.rs:25:1 - | -LL | / fn many_small_arrays() { -LL | | -LL | | -LL | | let x = [0u8; 500_000]; -... | -LL | | black_box((&x, &x2, &x3, &x4, &x5)); -LL | | } - | |_^ - | - = note: allocating large amounts of stack space can overflow the stack +error: this function may allocate 250$PTR bytes on the stack + --> tests/ui/large_stack_frames.rs:27:4 + | +LL | fn many_small_arrays() { + | ^^^^^^^^^^^^^^^^^ +... +LL | let x5 = [0u8; 500_000]; + | -- `x5` is the largest part, at 500000 bytes for type `[u8; 500000]` + | + = note: 250$PTR bytes is larger than Clippy's configured `stack-size-threshold` of 512000 + = note: allocating large amounts of stack space can overflow the stack and cause the program to abort = note: `-D clippy::large-stack-frames` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::large_stack_frames)]` -error: this function allocates a large amount of stack space - --> tests/ui/large_stack_frames.rs:36:1 +error: this function may allocate 1000000 bytes on the stack + --> tests/ui/large_stack_frames.rs:37:4 + | +LL | fn large_return_value() -> ArrayDefault<1_000_000> { + | ^^^^^^^^^^^^^^^^^^ ----------------------- this is the largest part, at 1000000 bytes for type `ArrayDefault<1000000>` + | + = note: 1000000 bytes is larger than Clippy's configured `stack-size-threshold` of 512000 + +error: this function may allocate 100$PTR bytes on the stack + --> tests/ui/large_stack_frames.rs:42:4 | -LL | / fn large_return_value() -> ArrayDefault<1_000_000> { -LL | | -LL | | -LL | | Default::default() -LL | | } - | |_^ +LL | fn large_fn_arg(x: ArrayDefault<1_000_000>) { + | ^^^^^^^^^^^^ - `x` is the largest part, at 1000000 bytes for type `ArrayDefault<1000000>` | - = note: allocating large amounts of stack space can overflow the stack + = note: 100$PTR bytes is larger than Clippy's configured `stack-size-threshold` of 512000 -error: this function allocates a large amount of stack space - --> tests/ui/large_stack_frames.rs:42:1 +error: this function may allocate 100$PTR bytes on the stack + --> tests/ui/large_stack_frames.rs:48:13 | -LL | / fn large_fn_arg(x: ArrayDefault<1_000_000>) { -LL | | -LL | | -LL | | black_box(&x); -LL | | } - | |_^ +LL | let f = || black_box(&[0u8; 1_000_000]); + | ^^^^^^^^^^^^^^----------------^ + | | + | this is the largest part, at 1000000 bytes for type `[u8; 1000000]` | - = note: allocating large amounts of stack space can overflow the stack + = note: 100$PTR bytes is larger than Clippy's configured `stack-size-threshold` of 512000 -error: aborting due to 3 previous errors +error: aborting due to 4 previous errors |